I am smart enough to know that then and now. I am only repeating what I heard with my own ears. But I wasn't about to stand up and tell the entire company the instructor giving the class didn't know what he was talking about. Had I done that, I would still be at MCRDSD in a Motivation Platoon. And I don't think the 180 tumble/yaw thing is particular to an m-16 with a 55 gr bullet. I've cut a few rounds out of animals when skinning them and most all bullets seem to do what they want once inside a target.